Fix all usages of setlocale: setlocale might (and on linux DOES)

Fix all usages of setlocale: setlocale might (and on linux DOES)
return a pointer to memory handled internally by libc, calling
setlocale twice and using the data returned from the first call
later on causes access to already free'd memory. This was clearly
seen through valgrind. Eg. use

  TESTS_STYLE=valgrind ./tests/tune2

with this cs backed-out and you will see valgrind problems
related to setlocale.